Grand Slam champion John Newcombe tells The Age that he expects world No. 1 Novak Djokovic to have a hard time at the start of the 2012 season, and could see No. 3 Roger Federer re-taking the top spot.

"Djokovic is really going to struggle the first six months of next year—he's really knocked himself out,'' said Newcombe. "He's just won so many matches, and it's been pretty obvious, even at the U.S. Open, he was struggling. I even thought he was struggling at Wimbledon against Bernard [Tomic], but he was able to pull himself together. He was very lucky to win the U.S. Open, because Roger [Federer] should never have lost that match from where he was. And now since the U.S. Open, there's injuries, a sore shoulder, a sore back, and when you watch him playing, he's running on three cylinders, so I'd say that his body, it's given in. I think it will be a superhuman effort for him to repeat the six months that he had. It was an amazing run, and that is very hard to defend. It's not going to surprise me if, by the end of July next year, Roger is very close to being No. 1 again."

Newcombe is not sure of No. 2 Rafael Nadal’s future. The Spaniard lost to Djokovic in the Wimbledon and U..S Open finals, as well as in four other 2011 tournaments.

"With Rafa, it's like the heavyweight champion of the world that's never been knocked out, and suddenly, gets knocked out six times within the space of six months by Djokovic," said Newcombe. "He doesn't have the same self-belief any more. All of a sudden he's having to face things, questions, that he's never doubted. So it's a question of can he get his head around this whole thing, and come back to where he was?"